So, I pulled out the plug guages and measured the throats on my revolvers....

[John C]

As the title says, I pulled out my plug guages and measured the throats on my revolvers.

All in all, they look good. Two of my Ruger .45 colt cylinders are going to cylindersmith.com for a throat job. They measure .450.

I have two questions: First, I noticed that one of the cylinders on a .45 LC Redhawk (bought used) had a ding on the mouth of one of the throats. The metal is ever so slightly dished out over the mouth, preventing my plug guage from passing though, although it would go all the way in that point from the chamber end. Is there any way to get that out? Or do I need to send it to cylindersmith.com and have it reamed, as well? The throats were measuring .451, so perhaps a throat job to .4525 would help accuracy.

Second, two of my newer smith .44 mags had throats that measured .429. Although on the small side, they are within spec (my '70s era Smiths all came in at .432). My guess is that they won't shoot cast bullets well. My question is, what's the optimum throat diameter for .429 jacketed bullets? Should I just limit these revolvers to jacketed bullets, or will it be worth it to get the throats reamed to .4305 or .4325?

Thanks,

-John

 

[Walkalong]

That little ding in the Redhawks throat is going to cause minor problems at least. Reaming is the best way to fix it. You could do it by hand, but the result would probably, well, almost assuredly, not be any better. Ream it and it will be right for sure.


My guess is those Smiths won't shoot lead all that well either, but you may get by. Just have to try it. If you want to shoot lead in them you should really get the throats reamed to .015 to .002 over bore diameter. Slug your bore, do not assume what it is.

 

[Slamfire]

Second, two of my newer smith .44 mags had throats that measured .429. Although on the small side, they are within spec (my '70s era Smiths all came in at .432). My guess is that they won't shoot cast bullets well. My question is, what's the optimum throat diameter for .429 jacketed bullets?

I have a M629-4 that has those tight chamber mouths. I found from Reloader Magazine that S&W made extra tight chamber mouths for a while, because the exceptional accuracy they measured from testing.

I have a good idea why they went back to the larger chamber mouths: pressure. I had to cut my loads with the M629. But the sucker is so exceptionally accurate, I can live with it.

And I am talking about lead bullets.

I would much rather cut my loads than screw up an accurate firearm!

Before you got out and have someone ream your chamber mouths, go out and shoot the revolvers. If they shoot well, leave them alone.

 

[snuffy]

So you know what the cylinder throats are. That's a good beginning. What are the bores of the barrels? Have you slugged them?

Matching the throats to the barrel is most important, not just making them uniform, or to some pie in the sky "normal". If you want to shoot lead accurately from a wheel gun, you need to have the cylinder throats AND the bore of the barrel matched.

 

[John C]

Thanks, guys for the info.

Snuffy; I hear what you're saying, but I'm approaching this from a different angle, although my next step is to slug (some of) my bores. I just wanted to understand where my chamber throats currently are, and whether they're uniform. Thankfully, I don't have any cylinders with mismatched throat diameters.

The ones that are .432, nothing remains to be done, since it's not really practical to go larger. The ones that are .450 need to be reamed, since, from what I understand, this will swage down a .452 (my usual diameter) cast and .451 jacketed bullets too far for optimum accuracy. Since right now my discretionary funds are a bit tight (everyone got a pay and benefit cut at work, due to the economy), I can only send a couple of cylinders to get get reamed, so I thought I'd identify any that are obviously out-of-spec. A project down the road is to figure what to do with my revolvers that are guaging at .451 and .429. Lots of shooting will determine whether they get reamed.

Slamfire; Interesting. Have you slugged your bore? I'm wondering if your bores are right at .429, so there's no mismatch between throat and bore? This is one where I'm going to slug the barrel to understand that relationship in my revolver. Also, what diameter cast bullets are you using? I have a large number of commercial .431 bullets, so my concern is the swaging down of bullet in the throat vs. the bore diameter of the barrel.

Walkalong; Thanks for the info. You're right, I'll probably just send that cylinder off to cylindersmith.com along with the others. It's already measured at .451, acceptable at this point, but that ding means that I'll just have it reamed out to .452 to even up the throats. I don't want to have a revolver with one "bad" chamber.

Thanks again, guys.

-John